Chapter 4; Tissues/Histology, (EPITHELIAL TISSUE-EPITHLIUM-EPITHELIA)

simple cuboidal epithelium

consist of a single layer of cells as tall as they are wide. Important functions are secretion and absorption. This epithelium forms the walls of the smallest ducts of glands and of many kidney tubules.

Explain what is meant by the phrase, "epithelium forms boundaries between environments".

nearly all substances received or given off by the body must pass through an epithelium.

stratified squamous epithelium

composed of several layers, it is thick and well suited for its protective role in the body. This epithelium forms the external part of the skin and extends a short distance into every body opening that is directly continous with the skin. Protects underlying tissue in areas subjected to abrasion. located in moist linings of the esophagus, mouth, and vagina. The Keratinized (karitin) forms the epidermis of the body.

Describe the basic shape that all endothelia cells have in the transverse plane...

epithelial sheet looks like a honeycomb.

simple squamous epithelium

flattened laterally, resemble tiled floor, and resemble fried eggs. Thin and often permeable, simple squamous epithelium is found where filtration or the exchange of substances by rapid diffusion is a priority. In the kidneys, forms part of the filtration membrane. In the lungs, it forms the walls of the air sacs across which gas exchange occur

Explain, in general terms, what is meant by, "epithelium covers and lines" and give some examples.

forms outer layer of the skin, dips into and lines the open cavities of the urogenital, digestive, and respiratory systems; and covers the walls and organs of the ventral body cavity.

Stratified Columnar epithelium

found in the pharynx, the male urethra, and lining some glandular ducts.

Explain what type of epithelium doesn't meat the previous definition in No. 1 and discuss the function of this type of epithelium provides.

glandular epithelium, which fashions the glands of the body

simple columnar epithelium

is a single layer of tall, closely packed cells, aligned like soldiers in a row. It lines the digestive tract from the stomach through the rectum. Columnar cells are mostly associated with absorption and secretion. Dense microvilli = absorptive cells Tubular glands = secrete mucus containing intestinal juice.

Explain what a microvilli is and what its function is.

microvilli are fingerlike extensions of the plasma membrane. Its function is to absorb or secrete (export) substances. examples the lining of the intestine or kidneys tubules.

Explain what functions epithelium can perform as an interfacing tissue.

protection, absorption, filtration, excretion, and sensory reception

Stratified Cuboidal epithelium

rare in the body, mostly found in the ducts of some of the layer glands (sweat glands, mammary glands) typically has two layers of cuboidal cells.

transitional epithelium

stretches readily, permits stored urine to distend urinary gland. lines the ureters, bladder, and part of the urethra. resembles both stratified squamous and stratified cuboidayl

Describe what functions simple epithelium is concerned with.

with absorption, secretion, and filtration.

Simple squamous, simple cuboidal, simple columnar, pseudostratified, stratified squamous, stratified cuboidal, stratified columnar and transitional epithelium. Describe the morphology (shape/appearance) of the fore mentioned tissues and be able to identify diagrams or photomicrographs of each

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Describe what is meant by the term polarity using the words "apical and basal surface"

Apical surface, an upper free surface exposed to the body exterior (or the cavity of an internal organ) and the lower attached is the basal surface.. The two differ in both structure and function. For this reason, we say that epithelia exhibit "apical-basal polarity"

Describe "reticular lamina" and explain its function

Reticular lamina is a layer of extracellualr material containing a fine network of collagen protein fibers that "belong to" the underlying connective tissue. It's function is to reinforce the epithelial sheet, helps it resist stretching and tearing, and defines the epithelial boundary.

Explain the difference between simple and stratified endothelium

Simple epithelia consist of a single cell layer. Stratified epithelia is composed of two or more cell layers stacked on top of each other. Simple epithelia are found where absorption, secretion, and filtration occur and a thin epithelial barrier is desirable. Stratified epithelium is found where protection is important, such as the skin surface, and the lining of the mouth.

Describe and name the three basic common shapes of endothelial cells

Squamous cells are flattened and scalelike (squale= scale) Cuboidal cells are boxlike, approximately as tall as they are wide. Columnar cells are tall and column shaped.

Describe what "tight junctions and desmosomes" are and explain their function and importance

Thight junctions and desmosomes are epithelial cells that fit closely together to form continuous sheet, bind adjacent cells together at many points. The tight junctions help keep proteins in the apical region of the plasma membrane from diffusing into the basal region, and thus help to maintain epithelial polarity

pseudostratified columnar epithelium

all of its cells rest in the basement, vary in height, but only the tallest reach the free surface of the epithelium. The tissue give a false impression because of the nuclei lie at different levels above the basement membrane. Secretes or absorbs substances. found in the Trachea, lines mosth of the lines in the respiratory tract, traps mucus, and prevents it from getting into the lungs.